1. Field of the Invention
The present invention relates to a semiconductor device, especially a method for manufacturing the semiconductor device of which a transistor and a MNOS type memory transistor, each of which has a different gate withstand voltage and drain withstand voltage, are included in the same semiconductor layer.
2. Related Art
In a manufacturing process for high-breakdown-voltage transistor, a high temperature process to form a deep well and a thick gate insulation layer is required as compared with a low-voltage-drive transistor. The high temperature process is specific for a forming process for low-voltage-drive transistor. Thus, conventionally, a high-breakdown-voltage transistor for high voltage operation and a low-voltage-drive transistor are individually formed.
Recently, research and development of so-called SOC (System On Chip), by which system functions conventionally achieved by a combination of IC in multiple numbers are realized in one IC chip, has been carried out.